Arrangement of rear hoists for motor vehicles

ABSTRACT

A hoist platform at the rear of a vehicle is mounted at the free ends of two pairs of arms forming a &#39;&#39;&#39;&#39;parallelogram&#39;&#39;&#39;&#39; linkage for raising and lowering the platform in a horizontal position. A linkage connected to the inner ends of one pair of arms causes the platform to tip down at ground level to facilitate loading. An adjustable cam is provided on the platform, the cam engaging the linkage, so that the platform can be made horizontal when the vehicle is on a slope.

United States Patent [72] Inventor Sten Magnus Bunge J akobsberg, Sweden [21] App]. No. 19,783 [22] Filed Mar. 16, 1970 [45] Patented Dec. 28, 1971 [73] Assignee AB Hydro-Lift Eskilstuna, Sweden [32] Priority Oct. 21, 1969 [33] Sweden [31] 14390 [54] ARRANGEMENT OF REAR HOISTS FOR MOTOR VEHICLES 6 Claims, 4 Drawing Figs.

[52] U.S. Cl 214/77 P [51] Int. Cl 860p 1/44 [50] Field of Search 214/77, 77

P, DIG. 10,75 T

[56] References Cited UNITED STATES PATENTS 2,822,938 2/l958 Ormsby 2l4/77P 3,065,868 11/1962 Novotney 214/77 P 3,175,707 3/1965 Mathers 214 77 P 3,258,140 6/1966 Appleman .214 77 P FOREIGN PATENTS 1,027,999 5 1966 Great Britain 214/77 P 155,590 8/1956 Sweden 214 77 P Primary ExaminerGerald M. Forlenza Assistant Examiner-Robert J. Spar Atlorney--Holman, Glascock, Downing & Seebolcl PATENTED DEC28I97I SHEET 1 0F 2 I INVENTOR M w 5 W w N m W & v w

PATENTEDUECHHQ?! 3630395 sum 2 OF 2 I INVENTOR MAG/W15 BUNQE.

Wfiawwmw aiy? I AQiR NEY ARRANGEMENT F REAR HOISTS FOR MOTOR VEHICLES The present invention relates to vehicles provided with rear hoist platforms.

It is known in rear hoist platforms for motor vehicles, in which the hoist platform is mounted at the outer ends of two pairs of parallelogram lifting arms, to make the hoist platform lean backwards, that is to say, tip downwards, when the liftingarm pairs rest upon the surface of the ground with their swiveling outer ends, so that a heavy parcel can be easily pushed up on to the platform, which is caused to assume a horizontal position at the beginning of the lifting movement and retain this position throughout the lifting operation.

A number of various devices have been proposed for this purpose, for instance, unequally varying the length of the one lifting arm in each pair of lifting arms.

it has proved that these arrangements operate well so long as the vehicle on which the rear hoist is mounted in standing during the loading upon a horizontal roadway. When the vehicle is standing during the loading upon a slope, the arrangement does not work well, and the worse the steeper the slope.

It is an object of the present invention to provide an arrangement whereby this inconvenience is completely overcome.

According to the invention there is provided in a vehicle comprising a hoist platform mounted on two pairs of parallelogram lifting arms at the rear of the vehicle, means to raise and lower the platform in at least a nearly horizontal position and means to tip the platform downwardly when lowered to the ground, the improvement comprising an adjustably rotatable cam mounted on the platform to engage a vertical connecting link between the lifting arms to vary the angle Other features, advantages and objects of the invention will be apparent from the following description of an embodiment of the invention, given by way of example only and without any limiting effect, with reference to the accompanying drawings, in which:

FIG. 1 shows a form of embodiment of a rear hoist according to the invention during lifting with the hoist platform in the normal position, i.e., when the vehicle is standing upon a horizontal roadway and is seen from the side;

FIG. 2 shows the same, but with the hoist platform in the position which it assumes when the vehicle is standing upon a downward slope;

FIG. 3 shows the same as FIG. 1, but with the hoist platform in the position which it assumes when the vehicle is standing upon an upward slope, and

FIG. 4 shows a side view of the suspension device of the hoist platform on a larger scale.

Referring to the drawings, the rear end of a vehicle is shown schematically in FIG. 1. Upon the underside ll of the vehicle frame is mounted a transverse shaft 12, which is rotatably borne by supports l3 and is adapted to be turned by means of an arm 14 which is fixed thereto and may be operated, for example, by an hydraulic cylinder 15. Rigidly secured to the shaft 12 are two short arms 16, whose free ends are joined by means of pivots 17 each to a corresponding one of two lower lifting arms 3. Two upper lifting arms 2 are pivotally mounted each at one end upon gudgeon pins 18 in the supports 13. The free outer ends of the arms 2, 3 are interconnected by means of links 8, mounted upon transverse shafts 4, 19. The distance between the axes of the shafts l2 and 18 is precisely the same as the distance between the axes of the shafts 4, 19. The arms 16 are provided with abutments 20, so placed that the distance between the shaft 12 and the shafts 19 is equal to the distance between the pivots l8 and the shafts 4 when an extension 21 of the lower lifting arms 3 is bearing against the abutment 20, but becomes shorter when the arms 16 have been pivoted counterclockwise under the frame 11. This shortening can be achieved only if the lifting arms 2, 3 are in their lowermost position and rest upon the ground with their free outer ends, causing the rear free end of the hoist platform 1 to sink until it,

too, rests upon the round, which considerably facilitates the loading of large and eavy parcels. Thereafter, as the arms 2, 3

are pivoted up, first the extension 21 is brought to rest against the abutment 20, whereby the hoist platform 1 is made to assume a position parallel to the surface of the ground, which it then retains during the continued uplift.

The hoist platform 1 is provided at its inner end and upon its underside with two ears 5, in which is mounted a transverse shaft 22, fixed whereupon is at least one eccentric 6, the perimeter 7 of which is adapted to bear at least against one of the links 8. The shaft 22 is adapted to be rotated by means of a lever 9, whose free end is equipped with a crank 10, made operable by hand or by means of a preferably hydraulic servomotor. The eccentric 6 is so mounted that the hoist platform I can be caused by rotating the eccentric 6 to lean both up and down relatively to the surface of the ground and so dimensioned that the hoist platform can be brought into a horizontal position when the vehicle is practice.

It has proved advantageous to give the eccentric 6 such an eccentricity and make it of such a material as to make it selflocking in any angular position, even if the hoist platform carries its maximum load.

Although only one form of embodiment has been shown and described above, other forms are possible within the scope of the invention.

lclaim:

1. In a vehicle having an attachment comprising a hoist platform pivotally mounted on two pairs of parallelogram lifting arm linkages which, in turn, are pivotally mounted at the rear of the vehicle, means to raise and lower the platform in an at least nearly horizontal position and means to tip the platform downwardly when lowered to the ground, the improvement comprising an adjustably rotatable cam mounted on the platform and engageable with a vertical connecting link between the free ends of the parallelogram lifting arm linkage to vary the angle of the platform during raising and lowering.

2. In a vehicle having an attachment comprising a hoist platform at the rear of the vehicle, an upper pair of platfonn-lifting arms, a lower pair of platform-lifting arms, means pivotally connecting outer ends of both pairs of platform-lifting arms to the platform, means pivotally connecting inner ends of one pair of the platform-lifting arms to support-means on the vehicle, a further pair of arms secured on a rotatable shaft, power means to rotate the shaft, means pivotally connecting inner ends of the lowerpair of the platform-lifting arms to said further pair of arms, abutment means on said further pair of arms to abuttingly engage said lower pair of the platform-lifting arms when raising the platform from and when lowering the platform to a ground-engaging position so that said lower pair of the platform-lifting arms rotate about the axis of said shaft, means to pivot the platform downwardly when in the groundcngaging position and disengage said abutment means with rotation of said shaft, the improvement comprising an adjustably rotatable cam mounted on the platform and engageable with link means connected between said outer ends of the pairs of platform-lifting arms, the cam being adjustable to position the platform horizontally when the vehicle is on a slope.

3. The improvement according to claim 2, wherein the inner ends of the upper pair of platform-lifting arms are pivotally connected to said supports on the vehicle and the inner ends of the lower pair of platform-lifting arms are pivotally connected to said further pair of arms.

4. The improvement according to claim 2, wherein the cam is in the form of an eccentric number of circular cross section.

5. The improvement according to claim 2, wherein a lever is connected to the cam for rotation of the cam.

6. The improvement according to claim 2, wherein the cam is so dimensioned as to be self-locking in all positions. 

1. In a vehicle having an attachment comprising a hoist platform pivotally mounted on two pairs of parallelogram lifting arm linkages which, in turn, are pivotally mounted at the rear of the vehicle, means to raise and lower the platform in an at least nearly horizontal position and means to tip the platform downwardly when lowered to the ground, the improvement comprising an adjustably rotatable cam mounted on the platform and engageable with a vertical connecting link between the free ends of the parallelogram lifting arm linkage to vary the angle of the platform during raising and lowering.
 2. In a vehicle having an attachment comprising a hoist platform at the rear of the vehicle, an upper pair of platform-lifting arms, a lower pair of platform-lifting arms, means pivotally connecting outer ends of both pairs of platform-lifting arms to the platform, means pivotally connecting inner ends of one pair of the platform-lifting arms to support-means on the vehicle, a further pair of arms secured on a rotatable shaft, power means to rotate the shaft, means pivotally connecting inner ends of the lower pair of the platform-lifting arms to said further pair of arms, abutment means on said further pair of arms to abuttingly engage said lower pair of the platform-lifting arms when raising the platform from and when lowering the platform to a ground-engaging position so that said lower pair of the platform-lifting arms rotate about the axis of said shaft, means to pivot the plaTform downwardly when in the ground-engaging position and disengage said abutment means with rotation of said shaft, the improvement comprising an adjustably rotatable cam mounted on the platform and engageable with link means connected between said outer ends of the pairs of platform-lifting arms, the cam being adjustable to position the platform horizontally when the vehicle is on a slope.
 3. The improvement according to claim 2, wherein the inner ends of the upper pair of platform-lifting arms are pivotally connected to said supports on the vehicle and the inner ends of the lower pair of platform-lifting arms are pivotally connected to said further pair of arms.
 4. The improvement according to claim 2, wherein the cam is in the form of an eccentric number of circular cross section.
 5. The improvement according to claim 2, wherein a lever is connected to the cam for rotation of the cam.
 6. The improvement according to claim 2, wherein the cam is so dimensioned as to be self-locking in all positions. 